This project deals with the development of new methods to synthesize multifunctional thiol ester derivatives. In Part I we intend to examine new methods to convert carboxylic acids to thiol esters. Part II considers alkylation and condensation reactions of thiol esters including new methods to prepare alpha, beta-unsaturated thiol esters, beta-keto thiol esters, beta-hydroxy thiol esters, glycidic thiol esters, alpha-arylseleno thiol esters as well as other functional combinations. Preparation of alpha-methylene-gamma-thiobutyrolactones is also proposed in Part II. Part III deals with the use of oxathiolane derivatives as intermediates in the preparation of thiol esters. The based induced conversion of S-alkyl-1, 3-oxathiolan-3-ium salts to thiol esters will be studied. Similarly new methods for making thirl esters will be developed using 1,3-oxathiolan-2-ylium salts. Due to the inherent reactivity of the thiol ester group, these thiol ester derivatives are of interest as potential antitumor agents. BIBLIOGRAPHIC REFERENCES: J. Wemple, "The Reaction of Thiol Esters with Lithium Diisopropylamide. Condensation Reactions of Thiol Ester Enolates," Tetrahedron Lett., 3255 (1975). D.J. Dagli, P.S. Yu and J. Wemple, "Darzans Synthesis of Glycidic Thiol Esters. Formation of a beta-Lactone By-product," J. Org. Chem., 40, 3173 (1975).